document.write( "Question 1210439: Trey wakes up late on average 4 days out of every 5. If Trey wakes up late, the probability that he is late for school is 90%. If Trey doesn't wake up late the probability that he is late for school is 25%. Create a tree diagram by entering the percentages and then calculate the percent chance that Trey gets to school on time.
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Algebra.Com's Answer #852548 by ikleyn(52969) $\"\"$ $\"About$

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\n" ); document.write( "Trey wakes up late on average 4 days out of every 5. If Trey wakes up late, the probability that he is late
\n" ); document.write( "for school is 90%.
\n" ); document.write( "If Trey doesn't wake up late the probability that he is late for school is 25%.
\n" ); document.write( "Create a tree diagram by entering the percentages and then calculate the percent chance
\n" ); document.write( "that Trey gets to school on time.
\n" ); document.write( "Enter your answers as a decimal or fraction between 0 and 1.
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\n" ); document.write( "\n" ); document.write( " I will not create a tree diagram. Instead, I will use my logic skills.\r
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document.write( "First, we have 4 days out every 5 days, when Trey wakes up late.\r\n" );
document.write( "In these 4 days, the probability that Trey gets school on time is (1-0.9) = 0.1.\r\n" );
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document.write( "So, these 4 days contribute   = 0.8*0.1 = 0.08  to the sough probability.\r\n" );
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document.write( "Next, we have 1 day out every 5 days when Trey doesn't wake up late.\r\n" );
document.write( "In this day, the probability he gets the school on time is (1-0.25) = 0.75.\r\n" );
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document.write( "So, this remarkable day contributes   = 0.2*0.75 = 0.15  to the sough probability.\r\n" );
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document.write( "Now we add two partial probabilities  0.08  and  0.15,  and we get the answer\r\n" );
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document.write( "    P = 0.08 + 0.15 = 0.23.\r\n" );
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document.write( "At this point, we complete the solution.\r\n" );
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